A user may wish to alter an image for many reasons. For example, the image may not have sufficient clarity and certain details may not be clearly visible, such as owing to dullness or a poor choice of colours. Moreover, image contrast, which generally relates to an entire image, may be unsatisfactory for allowing clear visualization of the details in one or more regions of the image. Zooming in a specific region can currently be done, but this does not allow visualization of local quantitative differences between pixels.
Alternatively, an image may be perceived as unattractive or unappealing. This is often due to the user's dislike of the colours of one or more parts of the image, or of one or more object within the image. If the user does not like the colours, or when the colours do not clearly show details the user wishes to see, changing the colours of parts or all of the image can be difficult or time-consuming.